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How to track down the source of Aborted_connects

 | August 23, 2008 |  Posted In: Insight for DBAs

Yesterday I helped someone who was seeing a lot of “server has gone away” error messages on his website. While investigating this problem, I noticed several things amiss, which appeared to be related but really weren’t. The biggest measurable sign was

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MySQL End Of Life (EOL) Policy

 | August 22, 2008 |  Posted In: Events and Announcements

We’ve discussed today how we should implement MySQL Version advisory in mk-audit tool. One obvious questions was to look at the end of life – it is often bad idea to run MySQL versions past end of life as even security bugs may not be fixed in these (though do not get paranoid, if you’re […]

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Multiple column index vs multiple indexes

 | August 22, 2008 |  Posted In: Benchmarks, Insight for DBAs

(There is an updated version of the content in this post by Percona’s Stephane Combaudon available here.) After my previous post there were questions raised about Index Merge on Multiple Indexes vs Two Column Index efficiency. I mentioned in most cases when query can use both of the ways using multiple column index would be […]

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How to find wrong indexing with glance view

 | August 21, 2008 |  Posted In: Insight for DBAs

Quite common beginners mistake is not to understand how indexing works and so index all columns used in the queries…. separately. So you end up with table which has say 20 indexes but all single column ones. This can be spotted with a glance view. If you have queries with multiple column restrictions in WHERE […]

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Rendundant Array of Inexpensive Servers

 | August 21, 2008 |  Posted In: Hardware and Storage

So you need to design highly available MySQL powered system… how do you approach that ? Too often I see the question is approached by focusing on expensive hardware which in theory should be reliable. And this really can work quite well for small systems. It is my experience – with quality commodity hardware (Dell,HP,IBM […]

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Worse than DDOS

 | August 18, 2008 |  Posted In: Insight for Developers

Today I worked on rather interesting customer problem. Site was subject what was considered DDOS and solution was implemented to protect from it. However in addition to banning the intruders IPs it banned IPs of web services which were very actively used by the application which caused even worse problems by consuming all apache slots […]

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Beware of MyISAM Key Cache mutex contention

 | August 12, 2008 |  Posted In: Insight for DBAs

Today I was working with the client loading data to MyISAM tables at very high rate. Hundreds of millions rows are loaded daily into single MySQL instance with bursts up to 100K of records/sec which need to be inserted (in the table with few indexes). It was good not all records had to go to […]

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Picking datatype for STATUS fields

 | August 9, 2008 |  Posted In: Insight for Developers

Quite commonly in the applications you would need to use some kind of “status” field – status of order – “new”, “confirmed”, “in production”, “shipped” status of job, message etc. People use variety of ways to handle them often without giving enough thought to the choice which can cause problems later. Perhaps worst, though quite […]

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